Experiment research on mechanical performance of bonded prestressed concrete continuous beam after elevated temperature

Abstract

Experiments on mechanical performance of nine bonded prestressed concrete (PC) continuous beams after elevated temperature are completed. The calculation method for normal section load-bearing capacity of PC beams after elevated temperature was established. The section of the beam was meshed into grid according to the distribution of temperature field, and the stress-strain relationship of concrete and steel after elevated temperature were introduced, and the moment-curvature of PC beam after elevated temperature was obtained based on equilibrium equations of force and moment on beam section. The moment, deflection and support displacement of the beam imposed by load (curvature) and support reaction together was calculated respectively, and the support reaction was calculated by secant stiffness matrix iteration method until the displacement compatibility equation at the support was satisfied, and the deflection of continuous beam could be obtained by curvature integral of cross section. The experimental results show that: the rate of load-bearing capacity degradation in mid-span section of PC beam after elevated temperature increases with the rise of heating time and load level and the decrease of concrete cover, and the rate of load-bearing capacity degradation in intermediate support increases with the rise of heating time and load level.